You know for all the talk of Turkey cozying up to either the Soviets or the west, I wonder what the likelihood is that they just end up going full isolationist post-war.
They could very well go full neutral and just willingly take the otl-Austria treatment.
Honestly, I don't think that 1945 Turkey has much say in the topic, Moscow, London and DC will decide.
Having said that, I think it is most likely that the Big Three will enforce a neutral Turkey. London cannot afford a pro-soviet Turkey and the Red Fleet to end up with access to open seas. Even the Americans will see the folly of that. At the same time, Stalin cannot afford a pro-West Turkey. Russia has been invaded twice in the span of a generation through Turkey/OE. And his own homeland was one of the targets in both cases. Moreover, to have NATO controlling Samsun and Sinop is a big no-no. In OTL Turkey was not a defeated enemy but a sovereign neutral country with a big army when the USSR was exhausted and devastated. They couldn't force her not to enter NATO, at best they could bluff. However, now Moscow has a say on the post war status of the country. And if they cannot make it into a satellite, then the next best option is neutrality.
Because I don't think they'll honestly be that devoted to territorial reclamation going forward
The problem is not that they lost land, but what kind of land was lost. From a security perspective, Greece having a big bridgehead in Anatolia is a grave threat. Imagine Italy losing Piedmont, Germany losing land on the right bank of the Rhine, of Britain losing Kent. Especially after losing a string of wars would rightly make any government paranoid of their security, especially when it comes to advantages of geography.
From an economic perspective it is the equivalent of Germany losing both Silesia and the Ruhr. The majority of 1913 ottoman exports came from TTL's Asiatic Greece and Thrace. If they lose most of their chrome to Kurdistan and Greece, the blow will be harder. I can see how the loss of those lands would translate into "they robbed us of our livelihood".
what must Turkish demographics look like by 1945?
That's a very good question.
Certainly a lot of young males have been casualties of war. Would it be more than other WW2 countries? I don't really know. The civilian population though should not have suffered much - at least compared to other Axis and Allied combatants. The Western Allies are either around the greco-turkish border or at the periphery of core territory (Slim and co). I doubt fighting will get close to major population centers before an armistice is signed. On the other hand, the treatment of the Red Army as it advances will be certainly brutal. However, even in their case I doubt they will advance further than e.g. Erzincan before an armistice. Therefore, I think that the vast majority of the civilian population will escape the horrors of war.